This invention relates to automatic embossing machines, and more specifically, to the die character wheel assembly of such machines.
There exist many types of machines for marking on substrates such as metal or plastic tags and the like. The resultant marks may comprise an imprint, which consists of a stamped impression, or an embossment, which consists of an impression on one side of the marked tag and a corresponding raised area on the other side of the tag. Machines that produce imprints typically have a punch and die element that addresses only one side of the tag, while the other side of the tag bears against a flat surface. Machines that produce embossments, however, require male and female punch and die elements that simultaneously bear against opposite sides of the tag. These types of machines, and the marks they produce, are well known in the art.
For various reasons, an embossed mark is generally desired on metal or plastic tags. The raised surface of the embossed mark facilitates reading of the mark when viewed from an angle, and also retards the obliteration of the mark from repeated paintings and coatings. With an imprinted mark, on the other hand, paint and dirt can rapidly fill in the impression to the point where the mark is rendered illegible. Additionally, a mark made within and below the surface is difficult to read when viewed from an angle.
The drawback to creating an embossed mark is that both a male punch and a female die are required to effect the raised mark on the surface of a tag. The punch and die must oppose each other on opposite sides of the tag. This type of arrangement is generally provided by a rotatable die character wheel assembly such as that shown in U.S. Pat. No. 3,263,789. This assembly comprises dual wheels with their inside faces opposed to each other, with one wheel bearing the male punch dies around its periphery and the other wheel bearing the female dies around its periphery. However, to synchronously rotate the die character wheels to allow for proper alignment of the respective punch and die for a particular character, the wheels are joined by a central integral hub. The hub also allows for the wheels to be spaced from each other to create a planar gap for passage through of the tag to be marked.
The punch and die activity actually takes place at a single location, because the die character wheels rotate to put the desired die character element in alignment with a plunger which punches down on the die character element to make the impression on the tag. The plunger itself is fixed at one location in the machine, so the die character elements must be individually moved into position under the plunger. Accordingly, the tag also must be moved so that the place on the tag which is to receive the embossment must be moved into position under the plunger.
Because of this central hub between the die character wheels, however, an obstruction is created which impedes the passage of the tag within the planar work area of the die character wheel assembly. Accordingly, the effective marking area on any tag is limited with respect to how far within the die character wheel assembly housing the tag can travel before it is obstructed by the central connective hub. This is a disadvantage with respect to how large a tag can be marked by embossing using a die character wheel assembly. Depending upon the size diameter of the die character wheel, the point furthest below the top edge of a tag to be marked is no greater than a few inches.
This limitation is unacceptable for many purposes which require an embossed tag larger than a few inches. For instance, tags to be used as identification plates for heavy equipment necessarily need to be large. Also, it is desirable that the discrete marking die characters be available in larger sizes. To accommodate larger size die characters, the corresponding effective work area should be increased.
Accordingly, there is a need for an embossing die character wheel assembly that can provide an unimpeded marking work area so that larger tags can be accommodated.